Django csrf token for Ajax

Question

I have given {% csrf_token %} inside the form. Do I have to give another {% csrf_token %} inside the AJAX $.ajax({ .......... )} ?

<form method="post" data-validate-username-url="{% url 'validate_username' %}">
    {% csrf_token %}
    {{ form.as_p }}
    <button type="submit">Sign up</button>
  </form>


    <script src="https://code.jquery.com/jquery-3.1.0.min.js"></script>


    <script>
    $("#id_username").change(function () {
      console.log($(this).val());
      var form = $(this).closest("form");
      $.ajax({
        url: form.attr("data-validate-username-url"),
        data: form.serialize(),
        dataType: 'json',
        success: function (data) {
          if (data.is_taken) {
            alert(data.error_message);
          }
        }
      });

    });
  </script>

Answer 1

The documentation very well explained how to use AJAX https://docs.djangoproject.com/en/2.1/ref/csrf/

1. Get this library https://github.com/js-cookie/js-cookie/
2. Add this var csrftoken = Cookies.get('csrftoken');

3. The last step is configure ajax setup

   function csrfSafeMethod(method) {
   // these HTTP methods do not require CSRF protection
    return (/^(GET|HEAD|OPTIONS|TRACE)$/.test(method));
   }
   $.ajaxSetup({
     beforeSend: function(xhr, settings) {
       if (!csrfSafeMethod(settings.type) && !this.crossDomain) {
           xhr.setRequestHeader("X-CSRFToken", csrftoken);
       }
     }
   });
   

Answer 2

Update to the steps above - as the Django documentation indicates you can use the Javascript Cookie library to do a Cookies.get('csrftoken'). Also, I had to add {% csrf_token %} before the function call. Might be obvious, but I didn't know so providing it here to help others

Answer 3

See below for how I changed your code. The csrf_token is assigned to a variable with Django templating. You can produce this variable in any of your Javascript code.

The token is then included in the header

 <script>
    var token = '{{csrf_token}}';

    $("#id_username").change(function () {
      console.log($(this).val());
      var form = $(this).closest("form");
      $.ajax({
        headers: { "X-CSRFToken": token },
        url: form.attr("data-validate-username-url"),
        data: form.serialize(),
        dataType: 'json',
        success: function (data) {
          if (data.is_taken) {
            alert(data.error_message);
          }
        }
      });

    });
  </script>